The present invention relates to a reflow apparatus and method which jets out hot gas flow to a circuit board to thereby solder the circuit board while transferring the circuit board into a plurality of sections in a reflow furnace along a transfer path.
A conventional reflow apparatus of the type referred to above is disclosed, for example, in Japanese Patent Laid-open Publication No. 2-137691(137691/1990) wherein a circuit board is heated in the gas and soldered while being transferred in a plurality of sections within a reflow furnace along a transfer path.
In the reflow apparatus of this kind, as shown in FIG. 25, a cream solder is fed to a circuit board 61 beforehand. After the circuit board 61 is moved into a reflow furnace 63 via an entrance along a transfer path 62, the circuit board 61 is moved through a first preheating section 64, a second preheating section 65, a reflow section 66 and a cooling section 69 along the transfer path. The circuit board 61 is gradually heated in the first and second preheating sections 64, 65, and is then further heated in the reflow section 66 to thereby be soldered. Reference numerals 67 indicate heaters arranged at predetermined intervals immediately above the transfer path 62 in each of the first preheating section 64, second preheating section 65 and reflow section 66.
In the above-described conventional reflow apparatus, since the heaters 67 are located close to the transfer path 62, a heated gas flow 70 which passes through the vicinity of the heaters 67 and a non-heated gas flow 71 which passes between the heaters 67 are not mixed with each other. The circuit board 61 on the transfer path 62 is eventually hit by the gas flows 70, 71 having differing temperatures and velocities, thus failing to satisfy the reflow condition.
An object of the present invention is to provide a reflow apparatus and method which can send gas flows of uniform temperature and uniform velocity to a circuit board moving along a transfer path.